1. Field of the Invention
The present invention relates to an electron emission display, and in particular, to an electron emission display which corrects the discrepancy in light emission efficiency and luminance between red, green and blue phosphor layers.
2. Description of the Related Art
Generally, electron emission elements are classified, depending upon the kinds of electron sources, into a first type using a hot cathode, and a second type using a cold cathode.
Among the second typed electron emission elements using a cold cathode, are a field emission array (FEA) type, a surface-conduction emission (SCE) type, a metal-insulator-metal (MIM) type, and a metal-insulator-semiconductor (MIS) type.
The FEA-type electron emission element is typically constructed with electron emission regions, and cathode and gate electrodes as the driving electrodes for controlling the emission of electrons from the electron emission regions. The electron emission regions are made from a material having a low work function or a high aspect ratio. When an electric field is applied to the electron emission regions made from such a material under a vacuum atmosphere, electrons are easily emitted from those electron emission regions.
In an electron emission device, arrays of the electron emission elements are arranged on a first substrate of the electron emission display device. A light emission unit is formed on a second substrate constructed with phosphor layers and an anode electrode, which is assembled with the first substrate, thereby forming an electron emission display device.
In the electron emission display device, the red, green and blue phosphor layers are provided to the corresponding pixels, and the light emissions of the phosphor layers are controlled, thereby displaying the desired color images at the corresponding pixels. The light emissions of the red, green and blue phosphor layers are controlled by varying the number of electrons emitted from the electron emission regions corresponding to the corresponding phosphor layers.
The red, green and blue phosphor layers differ from each other in light emission efficiency and luminance due to the different characteristics of the materials from which each phosphor layer is made, even though the same number of electrons are colliding against the red, green and blue phosphor layers.
For instance, in order to display a white color image, the red, green and blue phosphor layers should emit the same amount of light. For this purpose, the same number of electrons are emitted from the electron emission regions corresponding to the red, green and blue phosphor layers, and hit the corresponding phosphor layers. The red, green and blue phosphor layers, however, do not emit the same amount of light due to the discrepancy in light emission efficiency and luminance between the red, green and blue phosphor layers so that the desired white color image cannot be obtained at the relevant pixel. And this problem deteriorates the screen display quality of the electron emission display.
In order to solve this problem, it has been contemporarily proposed that the amount of electron emissions corresponding to the corresponding phosphor layers should be controlled in the aspect of the driving circuit to correct the discrepancy in light emission efficiency and luminance between the different-colored phosphor layers. This proposal, however, complicates the driving circuit structure.